The present invention generally relates to a semiconductor wafer, and more particularly to a semiconductor wafer having a region carrying information for identification. The present invention further relates to a method of providing on a semiconductor wafer a region carrying information for identification. Moreover, the present invention relates to a system and a method for identifying a semiconductor wafer having a region carrying information for identification.
The identification of semiconductor wafers is an important task before, during and after semiconductor wafer processing. For example, an identification of a wafer may be used to teach a process tool of the particular features of the special wafer so that process parameters can be adjusted accordingly.
In order to identify silicon wafers or other substrates in manufacturing or research facilities, the wafers are identified with a special marking. Such marking usually comprises a code, for example alphanumeric, T7, OCR and/or bar code. In this way, an individual wafer may be uniquely identified within a lot or a batch. Also, some raw silicon wafers have supplier marking, which is mostly alphanumeric, that identifies the pull, crystal or batch.
These special markings are usually provided by laser scribing. In order to retrieve the information, the marking is read by optical means.
Unfortunately, the optical information tends to disappear or to become unreadable during the processing of the wafer. In particular, extremely small and shallow markings tend to disappear after various film deposition steps over them. Also a laser scribe done prior to device processing tends to be come unreadable to naked eye, microscope or optical character readers due to this effect.
There are even more problems related to laser scribing. Such technique produces slag and particle defects on the wafer surface as a result of the scribing (pitting) process. Further, nucleation sites for silicon defects are created. The laser scribing allows contamination to collect in and around the scribe during processing. Further, the marking is typically located on the extreme wafer edge where film deposition is less stable and less uniform. The space that is needed for the laser scribing may reduce the usable space on the wafer surface. Markings on the backside of the wafer negatively impact the backside flatness.
Thus, laser scribing is problematic for wafer suppliers and manufactures of integrated circuits due to the techniques used, reading difficulties and the creation of defects and contamination.
The present invention seeks to solve the above mentioned problems by providing new devices, systems and methods by which a wafer may be uniquely identified.